It is known to provide flushing cisterns with two or more flushing volumes, which according to the prior art is allowed either by readjusting the filling level of the rinsing fluid in the cistern tank or by the lift of the bell moving up and downwards being adjustable. This requires, however, additional equipment and in fact it is simultaneously necessary to alter the lifting speed of the bell, too, the latter requiring that the user become familiar with the change.
U.S. Pat. No. 3,812,545 discloses a flushing cistern in which the cavity of the cistern bell is in open connection with a vertically extending air escape pipe carrying an adjustable air escape valve at its upper end inside the reservoir.